CBTC are modern railway signaling systems used in urban railway lines for light rail (e.g., tranvia), heavy rail (e.g., metro) and APM (Automated People Mover, e.g., Airport metros). Sometimes, they can be deployed also on commuter lines (rails going to suburban areas, e.g., S-Bhan). This document summarizes the main features that a generic CBTC shall support, based on the current IEEE standards and on the currently analyzed implementations